Numerous technologies for forming flat-panel displays are known in the art. One such technology is the electro-luminescent display, which is formed by coating a thin layer of electro-luminescent material between a pair of electrodes. Displays employing this technology produce light as a function of the current between the two electrodes when the electro-luminescent materials are electrically stimulated. One of the virtues of EL displays is the fact that they provide near-lambertian light emission. As a result, EL displays emit light over practically a full 180-degree field of view in both the horizontal and vertical dimension. This large angle of light emission is a virtue in that it allows multiple individuals to simultaneously view such a display from multiple viewing positions. It also allows individuals to view such a display without orienting it to one preferred viewing position. Unfortunately, because EL displays often provide luminance over a full 180-degree field of view in all directions, the display must consume enough power to create a high level of illumination at all angles. Therefore, such a display can require more power to create a given level of illumination at a preferred angle than other displays, such as liquid crystal displays, which often emit light over smaller viewing angles.
It is known to apply micro-lenses to EL displays, which focus the light from individual light-emitting elements into narrow cones of light, decreasing the power required to provide a desired level of luminance within the narrow cone of light as compared to an EL display having a very broad viewing angle. For example, Tutt et al., in U.S. Pat. No. 6,570,324, entitled, “Image display device with array of lens-lets” describes an organic light-emitting diode display having a sparse array of micro-lenses. Unfortunately these devices sacrifice the normally wide viewing angle that is typical in organic light-emitting diode displays.
Lee, in US Publication 2007/0091037, entitled “Energy efficient compact display for mobile device”, discusses the use of a sparse array of micro-lenses together with a much higher density array of light-emitting elements to steer light to the eyes of a user. As such, different light-emitting elements can be selected to steer the light to the eyes of the user, such that the user can perceive the display as having a very large field of view, even though the display only provides a small field of view at any moment. This ability to selectively adjust the field of view of the display allows the power consumption of the display to be reduced by significant amounts by reducing the field of view of the display, while providing the user with a perceptually broad field of view. Unfortunately, such a display requires a large number of individually-addressable light-emitting elements within each pixel. Moreover, with the technology available today, it is not possible to create a high-resolution display having numerous, individually-addressable light-emitting elements within each pixel.
There is a need to provide a display that has the improved power consumption of a narrow-angle display while at the same time, providing the ability to provide a display having a wide viewing angle. Such a display should not require a significantly higher density of light-emitting elements or increase the number or frequency of row and column drivers. Further, the display should not introduce undesirable artifacts.